Sage Journals: Discover world-class research

Abstract

Background:

Anterior cruciate ligament (ACL) injury is one of the most severe injuries for athletes. It is important to identify risk factors because a better understanding of injury causation can help inform athletes about risk and increase their understanding of and motivation for injury prevention.

Purpose:

To investigate the relationship between anatomic factors and risk for future noncontact ACL injuries.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

A total of 870, excluding 9 players with a new contact ACL injury and a player with a new noncontact ACL injury just before the testing, female elite handball and soccer players—86 of whom had a history of ACL injury—underwent measurements of anthropometrics, alignment, joint laxity, and mobility, including leg length, knee alignment, knee anteroposterior laxity, generalized joint hypermobility, genu recurvatum, and hip anteversion. All ACL injuries among the tested players were recorded prospectively. Welch t tests and chi-square tests were used for comparison between the groups (new injury group, which sustained a new ACL injury in the follow-up period, and no new injury group).

Results:

An overall 64 new noncontact ACL injuries were registered. No differences were found between athletes with and without a new ACL injury among most of the measured variables. However, static knee valgus was significantly higher in the new injury group than in the no new injury group among all players (mean difference [MD], 0.9°; P = .007), and this tendency was greater in players with a previous ACL injury (MD, 2.1°; P = .002). Players with secondary injury also had a higher degree of knee hyperextension when compared with those previously injured who did not have a secondary injury (MD, 1.6°; P = .007).

Conclusion:

The anatomic factors that we investigated had a weak or no association with risk for an index noncontact ACL injury. Increased static knee valgus was associated with an increased risk for noncontact ACL injury, in particular for secondary injury. Furthermore, hyperextension of the knee was a risk factor for secondary ACL injury.

Keywords

female soccer handball anterior cruciate ligament knee valgus hyperextension

Anterior cruciate ligament (ACL) injury is one of the most severe injuries for athletes, especially in cutting sports such as soccer, handball, and basketball, as it leads to prolonged absence from competition and often suboptimal performance.^57,62,65 Noncontact ACL injuries occur during cutting (change of direction) or 1-leg landing maneuvers,^30,41 especially in female athletes. One study reported a secondary ACL injury rate of 20% for athletes who return to a sport.⁶⁷ In other studies, patients with ACL reconstruction were at increased risk for the development of posttraumatic osteoarthritis and for knee arthroplasty in the mid- to long term.^8,33,64 Noncontact ACL injury has multiple risk factors, which can be modifiable and nonmodifiable.^4,14 Past studies have suggested various intrinsic factors, including high body mass, knee hyperextension, and anteroposterior (AP) laxity of the knee, as well as variations in knee anatomy, such as decreased ACL size, narrow intercondylar notch, increased posterior tibial slope, poor tibiofemoral congruity, and increased hip anteversion.^{1,4,38,51,59,66} Systematic review studies showed that generalized joint hypermobility in males and knee hyperextension increase ACL injury risk,^42,55 although the association between generalized joint hypermobility and risk for ACL injury is still controversial in females.⁵⁵ Moreover, injuries concomitant with ACL tears, such as medial collateral ligament injuries of grade ≥2,^56,68 lateral meniscus posterior root tears,^24,44 medial meniscus ramp lesions,^36,53 and anterolateral structure injuries,^52,58 are associated with residual rotatory laxity and have been shown to be risk factors for ACL failure, as well as younger age,¹³ increased posterior tibial slope,¹⁶ and knee hyperextension.¹⁹ Better understanding of risk factors, even nonmodifiable ones, is important to help inform players about risk and increase their understanding and motivation for injury prevention. Moreover, this information is crucial for orthopaedic surgeons to minimize failure risk after ACL reconstruction.

Unfortunately, our current knowledge is still limited. A prospective study analyzing the association between anatomic factors and noncontact ACL injuries in 859 cadets reported that primary ACL injury risk factors included small femoral notch width, generalized joint laxity, and, in women, higher body mass index and AP laxity of the knee. However, this study consisted of only 24 new noncontact ACL injuries, implying limited statistical power.⁵⁹ To our knowledge, no other prospective studies have comprehensively investigated anatomic risk factors in female elite athletes. The purpose of this study was to prospectively investigate the relationship between anatomic factors (eg, anthropometrics, alignment, joint laxity, and mobility) and risk for future noncontact ACL injuries. Although we could add hypotheses—for example, that joint laxity (including AP laxity), hyperextension of the knee, and generalized joint hypermobility are risk factors for new ACL injury—the current investigation can be considered an explorative analysis that was not designed to test specific hypotheses.

Methods

Study Design and Participants

This prospective cohort study investigated the risk factors for noncontact ACL injuries in elite female handball and soccer players from 2007 to 2015. In 2007, all teams in the Norwegian female handball premier league were invited to a comprehensive preseason baseline screening examination. Athletes with a first team contract who were expected to play in the premier league during the 2007 season were eligible for participation. New teams qualified for the premier league from 2008 to 2013, and players from the clubs were invited for preseason tests. From 2009, female elite soccer players were also included. The tested sample represented approximately 84% of eligible athletes based on data from the first year of testing.²⁹ In total, 880 players composed the cohort (handball, n = 429; soccer, n = 451; age, 14-37 years). Nine players with a new contact ACL injury were excluded. One player with a new noncontact ACL injury was excluded because she had no physical examinations owing to the ACL reconstruction that she had undergone 3 months before. Thus, 870 players were included in the analysis (Figure 1). Data were partly missing in 103 players for reasons such as ankle sprain sustained before the test, knee or Achilles pain, shortage of testing time, and problems with testing equipment. Demographic data such as age, mass, and height were collected at the time of a preseason screening examination. The Regional Committee for Medical Research Ethics, the South-Eastern Norway Regional Health Authority, and the Norwegian Social Science Data Services approved the study. All players gave informed consent before inclusion. Players aged <18 years provided parental consent.³¹

Figure 1.

Flowchart detailing the study protocol. ACL, anterior cruciate ligament.

The primary outcome variables of this prospective cohort were defined by Krosshaug et al.³¹ All measurements and procedures were performed as described in our previous study⁴³ and are therefore explained briefly.

Anthropometrics and Alignment

Skin Marker–Based Measurements: Leg Length, Pelvic Orientation, and Knee Alignment

All reflective markers were attached on anatomic landmarks or muscle bellies: bilateral posterior and anterior superior iliac spines, greater trochanters, lateral and anterior thighs, lateral femoral condyles, tibial tubercles, anterior and lateral lower legs, lateral malleolus, heels, and laterally and medially near the tips on the shoes.⁴⁰ From the static calibration trial, we defined each participant's natural posture and measured static knee valgus and varus alignment, femur and tibial length, and pelvis orientation (forward tilt, left tilt, left rotation) and width. For handball and soccer players, static alignment was measured while wearing their preferred indoor shoes.

The markers were used to estimate the participant's joint centers according to previous studies.^5,15,17 The length of the femur and tibia was measured from the center of the hip joint to the knee joint and from the knee joint to the ankle joint, respectively. The total leg length was measured from the center of the hip joint to the floor. The lengths were presented as a ratio of total body height. Assessment of the pelvic orientation was performed with the test participant standing in a standard anatomic position. The orientation of the pelvis was measured relative to the global system. Pelvis width was defined as the distance between the right and left anterior superior iliac spines and presented as a ratio of total body height. Static knee valgus angle was measured as the frontal angle among the hip, knee, and ankle joint centers.

Femoral and Tibial Condyle Width

The femoral and tibial condyle width were measured between the medial and lateral condyles of the knee. The distance was measured to the nearest 0.5 cm, using a caliper. The width was presented as a ratio of total body height.

Joint Laxity

Knee AP Laxity

The KT-1000 knee arthrometer was used to quantify the AP laxity of the knee as described previously.⁴⁰ The maximum value (in millimeters) in each knee was recorded from 2 trials. The reliability of the KT-1000 arthrometer by experienced raters has been shown to be good (intraclass correlation coefficient, 0.79).⁶ Based on the International Knee Documentation Committee guidelines, normal knee AP laxity was defined as a side-to-side difference ≤2 mm.²¹

Genu Recurvatum

Genu recurvatum (hyperextension of the knee) was measured with a standardized goniometer. The testers palpated the anterior and posterior parts of the lateral knee joint line and marked the midpoint of the sagittal plane (K). The most prominent part of the lateral ankle malleolus (M) and greater trochanter (T) was then palpated and marked. The axis of the goniometer was positioned above each point, and the angle formed by the line K-M and the line K-T was measured and the nearest degree recorded. Plus values (≥0°) indicated genu recurvatum.

Generalized Joint Hypermobility

The Beighton score (total 9 points) was used to evaluate generalized joint hypermobility.²³ Because of the analysis based on each leg, the Beighton score was calculated for each half of the body, and the forward touchdown was included for both halves of the body (score range, 0-5 points).

Mobility

Hamstring Mobility

Testing of hamstring mobility was performed on an examination table with a firm surface and lumbar support. The player was lying on the bench in the supine position with the pelvis and the nontested leg stabilized using belts to avoid accessory movements. The hip of the testing leg was fixed at 120° of flexion using a belt, and the player was supported against further hip flexion by the tester pressing with both hands distally on the femur. The ankle and foot were relaxed, and the hip was in neutral rotation, abduction, and adduction. Three landmarks were placed on the leg: lateral fibular malleolus, lateral femoral epicondyle, and greater trochanter of femur. The knee was extended passively with an 8-kg load, and a goniometer was placed to the point of the knee joint line. Flexibility was measured as static range of motion.

Hip Anteversion

The player lay in a relaxed prone position on a therapy bench and was fixed with a belt over her pelvis. One test person held the distal part of the player's tibia, passively flexed the knee to 90°, and then rotated the hip passively inward and outward until the most lateral and prominent part of the greater trochanter was identified by palpation. In this position, another test person measured the angle between the vertical line and the shaft of the tibia to the nearest degree using a standardized goniometer.⁴⁸

Navicular Drop

The navicular drop was defined as the distance that the navicular tuberosity moves in the standing position as the subtalar joint is allowed to move from its neutral position to a relaxed position. The height of the navicular tuberosity was measured in neutral and relaxed stance positions, and the total excursion was measured.³⁷

Injury Registration

All complete ACL injuries among the tested players were recorded through May 2015, primarily through semiannual contact with the participating teams (manager, coach, and medical staff). If any acute knee injuries occurring during regular team training or competition were reported, the injured player was contacted by phone to get detailed medical data and a description of the injury situation.²² Noncontact ACL injury, as defined in this study, also consisted of “indirect contact”: situations where player contact may have occurred before or at the time of injury but was not a direct blow to the knee (contact injury). All ACL injuries were confirmed by magnetic resonance imaging and/or arthroscopy.³¹

Statistical Analysis

The data were analyzed using the statistical software R Version 4.2.2. Descriptive data are presented as mean and standard deviation. A total of 870 players were divided into 2 groups: no previous ACL injury (784 players) and previous ACL injury (86 players). We analyzed 18 anatomic measurements as described earlier. Players were divided into 2 subgroups: new injury group, which sustained a new ACL injury in the follow-up period, and no new injury group. Welch t test and a chi-square test were used for comparison between the groups. Statistical significance was set at P < .05.

Results

Out of 880 players, 64 new noncontact ACL injuries were used in the analysis: 44 no contact and 20 indirect contact (Figure 1). Secondary ACL injuries occurred in 5 ipsilateral and 8 contralateral knees. The mean ± SD age at a new noncontact ACL injury during the study period was 21.9 ± 4.0 years. The mean duration from physical examination to a noncontact ACL injury was 1.9 ± 1.8 years. No player had a new noncontact ACL injury in both knees during the study period. Eight players had previous bilateral ACL injuries before testing.

Among the variables that were measured, we found only small or no differences between those who sustained a noncontact ACL injury and those who did not (Table 1). However, among all players, static knee valgus was significantly higher in the new injury group than in the no new injury group (0.2°± 2.6° vs −0.7°± 2.9°; P = .007), and this tendency was clearer in the previous ACL injury players (1.4°± 1.8° vs −0.7°± 2.9°; P = .002) (Figure 2A). Players with secondary injury also had a higher degree of genu recurvatum as compared with previously injured players who did not have a secondary injury (1.9°± 1.6° vs 0.3°± 3.0°; P = .007) (Figure 2B). No significant differences were found for KT-1000 arthrometer values and Beighton scores between groups with and without new injuries (Tables 1 and 2).

Table 1

Player Characteristics Classified According to Past and Current ACL Injury^a

	All			No Previous Injury			Previous Injury
	New Injury	No New Injury	P Value	New Injury	No New Injury	P Value	New Injury	No New Injury	P Value
No. of players	64	806		51	733		13	73
Age at testing, y	20.3 ± 3.7	21.0 ± 4.0	.12	19.5 ± 3.3	20.7 ± 3.9	.016	23.2 ± 3.7	23.8 ± 4.1	.59
Body mass, kg	67.5 ± 8.0	66.1 ± 7.9	.17	66.3 ± 7.4	65.9 ± 7.9	.76	72.5 ± 8.6	67.6 ± 8.3	.07
Height, cm	170.6 ± 7.0	169.5 ± 6.3	.23	170.1 ± 6.8	169.3 ± 6.2	.43	172.3 ± 7.5	171.1 ± 6.9	.59
No. of players (Range)^b	61-63	751-800		48-50	683-728		13	77-82
Degrees (static)
Knee valgus	0.2 ± 2.6	−0.7 ± 2.9	.007	−0.1 ± 2.7	−0.7 ± 2.9	.13	1.4 ± 1.8	−0.7 ± 2.9	.002
Pelvis forward tilt	15.0 ± 4.2	15.3 ± 4.6	.56	14.9 ± 4.3	15.5 ± 4.6	.34	15.6 ± 3.4	13.9 ± 4.1	.13
Pelvis left tilt	−0.4 ± 1.7	−0.5 ± 1.7	.80	−0.4 ± 1.8	−0.5 ± 1.7	.78	−0.4 ± 1.8	−0.4 ± 1.7	.85
Pelvis left rotation	0.7 ± 2.6	0.5 ± 2.8	.55	0.7 ± 2.7	0.5 ± 2.8	.55	0.7 ± 2.5	0.6 ± 2.8	.94
Percentage vs height
Pelvis width	14.0 ± 1.0	13.9 ± 1.1	.25	14.0 ± 1.0	13.8 ± 1.1	.38	14.2 ± 0.9	14.1 ± 1.1	.58
Leg length	52.9 ± 1.7	52.4 ± 1.8	.040	52.9 ± 1.7	52.4 ± 1.8	.08	53.0 ± 1.9	52.5 ± 1.7	.34
Femur length	24.9 ± 0.9	24.8 ± 0.8	.39	25.0 ± 0.9	24.8 ± 0.8	.29	24.8 ± 0.7	24.8 ± 0.8	.87
Tibia length	24.5 ± 1.0	24.5 ± 1.0	.61	24.4 ± 1.1	24.5 ± 1.0	.65	24.5 ± 0.8	24.7 ± 1.0	.69
Femur condyle width	5.3 ± 0.7	5.4 ± 0.7	.58	5.3 ± 0.8	5.4 ± 0.7	.56	5.3 ± 0.6	5.3 ± 0.7	.59
Tibia condyle width	5.1 ± 0.6	5.2 ± 0.6	.60	5.1 ± 0.6	5.2 ± 0.6	.66	5.1 ± 0.5	5.0 ± 0.6	.69
KT-1000, mm	7.0 ± 2.0	6.9 ± 1.9	.71	6.8 ± 1.9	6.8 ± 1.8	.99	7.8 ± 2.2	8.4 ± 2.6	.37
Genu recurvatum, deg	0.6 ± 3.1	1.0 ± 3.5	.46	0.3 ± 3.3	1.0 ± 3.5	.16	1.9 ± 1.6	0.3 ± 3.0	.006
Beighton score	1.1 ± 1.2	0.9 ± 1.0	.44	1.1 ± 1.3	0.9 ± 1.0	.22	0.8 ± 0.9	1.2 ± 1.1	.14
Hamstring mobility, deg	137 ± 12	139 ± 12	.38	137 ± 12	138 ± 12	.48	139 ± 9	143 ± 12	.12
Hip anteversion, deg	7.9 ± 4.6	9.4 ± 5.0	.014	8.0 ± 4.1	9.4 ± 5.0	.020	7.6 ± 6.2	9.4 ± 5.2	.35
Navicular drop, mm	50.2 ± 5.8	49.6 ± 4.7	.42	50.2 ± 5.9	49.6 ± 4.8	.45	50.3 ± 5.9	49.9 ± 4.7	.83

Data are presented as mean ± SD. P values are shown for univariate comparisons between players with and without a new noncontact ACL injury. Bold indicates P < .05. For players with new injuries, data are reported for the injured leg only (except age, body mass, and height). In the groups with no new injuries, data represent the mean of the left and right legs, although data among the players with previous injury represent the mean of the all previously injured legs. ACL, anterior cruciate ligament.

The number of tested players varied by test.

Figure 2.

Distribution of (A) static knee valgus and (B) knee extension angle in players with previous anterior cruciate ligament (ACL) injury (n = 86).

Table 2

SSDs of KT-1000 Arthrometer Values According to Previous and Current ACL Injury^a

	All			No Previous Injury			Previous Injury
	New Injury	No New Injury	P Value	New Injury	No New Injury	P Value	New Injury; I/C	No New Injury	P Value
SSD, mm			.90			.80			.56
≤2	52 (82.5)	667 (83.8)		44 (88.0)	630 (86.8)		8 (61.5); 2/6	37 (52.9)
>2	11 (17.5)	129 (16.2)		6 (12.0)	96 (13.2)		5 (38.5); 3/2	33 (47.1)

Data are presented as No. (%) of players. P values are shown for univariate comparisons between players with and without a new noncontact ACL injury. For all groups, the data represent SSD regardless of previous or new injury. ACL, anterior cruciate ligament; I/C, ipsilateral knee/contralateral knee; SSD, side-to-side difference.

Among all players, the new injury group had a significantly lower hip anteversion (7.9°± 4.6° vs 9.4°± 5.0°; P = .014) than the no new injury group, as did players with no previous injury (8.0°± 4.1° vs 9.4°± 5.0°; P = .020). Although a small difference among all players, leg length relative to height was significantly larger in the new injury group than the no new injury group (52.9% ± 1.7% vs 52.4% ± 1.8%; P = .040). Among the players with no previous ACL injury, those with a new ACL injury were significantly younger than those with no new ACL injury (19.5 ± 3.3 vs 20.7 ± 3.9 years; P = .016) (Table 1).

Discussion

The present study revealed that only a few anatomic risk factors were associated with an ACL tear in elite female athletes. AP laxity of the knee and generalized joint laxity were not found to be risk factors for either primary or secondary ACL injury. However, increased static knee valgus was associated with an increased risk for primary and secondary ACL injury, suggesting that noncontact ACL injury risk is related not only to movement patterns such as knee valgus and knee abduction moment at cutting/landing but also to frontal knee alignment. Furthermore, hyperextension of the knee was associated with an increased risk for secondary injury. To our best knowledge, the current study is the first prospective study to evaluate the association between secondary ACL injury and anatomic risk factors in elite female athletes.

Previous studies^27,34 suggested that frontal plane biomechanics plays an important role for noncontact ACL injury risk in sports. Results from the current study indicate that injury risk is related not only to movement patterns of high knee abduction moment at cutting/landing but also to anatomic lower limb alignment of the players. The static knee valgus angle was significantly greater in the new injury group than in the no new injury group for all players, but the difference was mainly driven by the players with a history of ACL injury (Table 1). This suggests that special attention should be given to ensure good knee alignment before and after surgery—for example, through appropriate treatment of concomitant injury that may affect valgus alignment, such as medial collateral ligament injury³⁵ and lateral meniscus tear,²⁰ and neuromuscular rehabilitation. However, it should be pointed out that we have no indications for unsuccessful surgery in players with secondary injury, because the group with no previously injured leg had slightly higher valgus (0.88°± 2.2°) than the group with a previously injured leg (0.69°± 3.0°). Nevertheless, the current study is clinically relevant because it implies that noncontact ACL injury risk is related not only to dynamic valgus in cutting/landing situations but also to frontal knee alignment.

Hyperextension of the knee (defined as genu recurvatum >0°) was not a risk factor for primary ACL injury in our cohort of elite female athletes (Table 1). This finding stands in contrast to previous studies that have suggested knee hyperextension to be a risk of primary ACL injury.^28,38,46 However, these studies either had smaller sample sizes as compared with the current study or were case-control studies with possible biases. Although the heterogeneous definition of hyperextension (recurvatum >0°, >5°, or >10°)^{11,12,18,38,46} should be taken into account when discussing studies on knee hyperextension, our study has far greater statistical power than previous studies. In contrast to primary ACL injury, knee hyperextension >0° was identified as a risk factor for secondary ACL injury, including new injury to the contralateral side (n = 8) in addition to graft rupture (n = 5). Furthermore, in recent studies, preoperative knee hyperextension >5° and >6.5° was identified as a risk factor for ACL hamstring tendon graft failure.^18,19 These authors measured passive knee hyperextension in the contralateral (healthy) knee at the time of the surgical procedure and under anesthesia, which may have contributed to the differences in the measured knee hyperextension between these studies and the present study. Therefore, it may be necessary to pay special attention to the presence of knee hyperextension in athletes with a history of ACL injury. Yet, it should be noted that the small sample size in our cohort in the analysis of secondary ACL injuries results in low statistical power.

Several studies have evaluated the association between primary ACL injury and AP laxity. Vacek et al⁶⁰ reported that for each additional millimeter in knee AP displacement present, there was 27% greater odds of sustaining an ACL injury (odds ratio, 1.27) among young female athletes. In contrast, in a prospective study, Uhorchak et al⁵⁹ observed no statistically significant difference in mean KT-2000 arthrometer results between young female cadets with and without an ACL injury. Shimozaki et al⁵⁰ and Vauhnik et al⁶³ also showed no significant difference of knee anterior laxity between female athletes with and without ACL injury. Taken with the results of the current study (Table 1), AP laxity of the knee is unlikely to be a risk factor for primary ACL injury among young female athletes. Moreover, focusing only on those with AP laxity >2 mm, which is considered abnormal knee laxity,²¹ did not change the outcome of the current study, as the proportion of players with high AP laxity was not increased in players with a new injury (Table 2).

In contrast to 2 previous studies, neither AP laxity (Table 1) nor side-to-side difference in AP laxity of the knee (Table 2) was found to be a risk factor for secondary ACL injury. Pinczewski et al⁴⁵ reported a side-to-side difference in AP laxity of >2 mm at 2 years after surgery to be associated with an increased risk for graft rupture in a 10-year follow-up study after ACL reconstructions. Moreover, Bourke et al⁹ reported that patients with a side-to-side difference of AP laxity >2 mm at 1 year postoperatively had a 2.9-fold risk of ACL retear at 15-year follow-up after ACL reconstruction. The discrepancy between the results of the aforementioned 2 studies and the present study might have originated from the fact that ACL secondary injuries in our study also include contralateral ACL injuries. In a further breakdown of the current results, the proportion of players with ACL reinjury and a side-to-side difference of AP laxity >2 mm was higher than that of players with no new ACL injury and a side-to-side difference >2 mm (60.0% [3/5] vs 44.8% [35/78]); however, in the current study, the limited number of reinjuries in the material prevents conclusive interpretation.

In the current study, generalized joint hypermobility was not a risk factor for primary or secondary ACL injury. A number of studies have suggested an association between generalized joint hypermobility and ACL injury.^{2,25,46,54,61} However, among only prospective studies on women, 1 study reported generalized joint hypermobility as a risk for primary ACL injury,⁵⁹ while 2 studies found no significant association.^51,60 As for secondary ACL injury, 1 prospective and 2 retrospective studies showed a higher incidence of either ACL graft rupture and contralateral ACL injury or ACL failure in patients with generalized joint hypermobility than in patients without generalized joint hypermobility.^25,26,32 Yet, in the present study, there was not even a tendency suggesting that there might be a difference between those with and without new noncontact ACL injury regardless of previous ACL injury; rather, the Beighton score, which is a reliable clinical assessment tool that shows acceptable reliability when used by raters of any background or experience level,⁷ tended to be slightly higher in the no new injury group. Even if the Beighton score was composed of the left and right sides to give a maximum score of 9, the mean Beighton score for the new injury group in the whole cohort would still be low at 2.2. It should be considered that the proportion of females with generalized joint laxity (Beighton score ≥4) may be lower in this study of elite female athletes than in the general female population (23% vs 51.0%, respectively).^10,47,49 The present prospective study has a larger sample size of female elite players and higher statistical power than previous studies. Therefore, our study revealed that generalized joint laxity is not a risk factor for ACL injury, at least among young elite female athletes in cutting sports.

The current study did not support a hypothesis from a previous study based on magnetic resonance imaging measurement suggesting that increased hip anteversion would increase ACL injury risk.¹ We found hip anteversion to be significantly smaller in players sustaining a new injury among players without a previous injury. There was a similar tendency among players with a previous ACL injury (Table 1). A prospective cohort study of 290 female high school basketball and handball players reported similar results (noncontact ACL group [15.3°] vs control group [16.6°]) and suggested that reduced femoral anteversion could be a risk factor for noncontact ACL injury.³⁹ Although we observed the same trend, the mean difference in hip anteversion between groups was only 1.5°, which indicates limited usefulness in clinical practice considering the measurement error. Given the error-prone nature of hip anteversion measurement, the association between hip anteversion and ACL injury risk is still controversial, and future studies based on more accurate testing methods will be needed.

Players who sustained a new ACL injury had longer leg length relative to their height as compared with the injury-free players (Table 1). Longer leg length is likely to result in higher external moment arms and may thereby contribute to increased knee abduction moment. However, the observed differences in leg length between players with and without a new injury corresponded to <1 cm and is therefore likely of limited clinical significance.

The present study has unique strengths when compared with previous risk factor studies because of the large sample size and homogeneous participants, including only female elite athletes. However, there are some limitations in the present study. First, errors in physical examination measurements and marker placements could have occurred. To minimize these errors, we used the same clinician for multiple testing years. Nevertheless, there were still several testers over the 8-year data collection period. In our reliability test conducted on 106 players in the same cohort with a 2-year interval, mean ± SD differences for knee static angle, genu recurvatum, and hip anteversion were −1.6°± 3.2°, 0.3°± 3.2°, and 8.6°± 3.7°, respectively. Second, some athletes might still be growing during the follow-up period, but with an average age of 21 years, this will likely have limited influence on our data. Third, follow-up periods varied among all players, and playing exposure times were not collected. Yet, as the percentage of players with a new injury in the cohort was as low as 7.9%, Cox regression analyses are not warranted.^3,31 Fourth, we decided to do simple univariate analyses in the current study, rather than investigating odds ratios using logistic regressions. We made this decision as the study power will not allow for the large number of outcome variables and possible adjustment factors. We had already conducted advanced machine learning analyses that showed poor predictive ability of future noncontact ACL injury, even when utilizing far more tests and variables among the 791 players in the current cohort.²² Fifth, no radiologic analysis including femoral notch size and proximal tibial slope was performed, as this was not practically possible in this data collection. Last, no detailed information was available on ACL reconstruction, including graft choice and surgical technique.

Conclusion

Most anatomic factors, including anthropometrics, joint laxity, alignment, and mobility, had a weak or no association with risk for primary noncontact ACL injury in elite female athletes. However, increased static knee valgus was associated with an increased risk for noncontact ACL injury, in particular for secondary injury. Furthermore, hyperextension of the knee was identified as an additional risk factor for secondary ACL injury. Yet, the number of players with secondary injury was limited, meaning that these results must be treated with caution.

Footnotes

Acknowledgements

The authors acknowledge all players in the Norwegian female premier soccer league and handball league for their participation in this study. We also thank members of the project group and research assistants who contributed to the data collection.

Submitted December 6, 2023; accepted September 4, 2024.

One or more of the authors has declared the following potential conflict of interest or source of funding: Funding was received from the Uehara Memorial Foundation Scholarship Grant for overseas research fellowships, the 34th research grant of the Nakatomi Foundation. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

References

Alpay

Ezici

Kurk

, et al. Increased femoral anteversion related to infratrochanteric femoral torsion is associated with ACL rupture. Knee Surg Sports Traumatol Arthrosc. 2020;28(8):2567-2571.

Anderson

Lipscomb

Liudahl

Addlestone

RB.

Analysis of the intercondylar notch by computed tomography. Am J Sports Med. 1987;15(6):547-552.

Annesi

Moreau

Lellouch

Efficiency of the logistic regression and Cox proportional hazards models in longitudinal studies. Stat Med. 1989;8(12):1515-1521.

Bayer

Meredith

Wilson

, et al. Knee morphological risk factors for anterior cruciate ligament injury: a systematic review. J Bone Joint Surg Am. 2020;102(8):703-718.

Bell

Pedersen

Brand

RA.

A comparison of the accuracy of several hip center location prediction methods. J Biomech. 1990;23(6):617-621.

Berry

Kramer

Binkley

, et al. Error estimates in novice and expert raters for the KT-1000 arthrometer. J Orthop Sports Phys Ther. 1999;29(1):49-55.

Bockhorn

Vera

Dong

, et al. Interrater and intrarater reliability of the Beighton score: a systematic review. Orthop J Sports Med. 2021;9(1):2325967120968099.

Bodkin

Werner

Slater

Hart

JM.

Post-traumatic osteoarthritis diagnosed within 5 years following ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2020;28(3):790-796.

Bourke

Gordon

Salmon

, et al. The outcome at 15 years of endoscopic anterior cruciate ligament reconstruction using hamstring tendon autograft for “isolated” anterior cruciate ligament rupture. J Bone Joint Surg Br. 2012;94(5):630-637.

10.

Clinch

Deere

Sayers

, et al. Epidemiology of generalized joint laxity (hypermobility) in fourteen-year-old children from the UK: a population-based evaluation. Arthritis Rheum. 2011;63(9):2819-2827.

11.

Cooper

Dunn

Huston

, et al. Physiologic preoperative knee hyperextension is a predictor of failure in an anterior cruciate ligament revision cohort: a report from the MARS Group. Am J Sports Med. 2018;46(12):2836-2841.

12.

Cooper

McAndrews

LaPrade

RF.

Posterolateral corner injuries of the knee: anatomy, diagnosis, and treatment. Sports Med Arthrosc Rev. 2006;14(4):213-220.

13.

Cristiani

Forssblad

Edman

Eriksson

Stålman

Age, time from injury to surgery and quadriceps strength affect the risk of revision surgery after primary ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2021;29(12):4154-4162.

14.

Davey

Vacek

Caldwell

, et al. Risk factors associated with a noncontact anterior cruciate ligament injury to the contralateral knee after unilateral anterior cruciate ligament injury in high school and college female athletes: a prospective study. Am J Sports Med. 2019;47(14):3347-3355.

15.

Davis

Õunpuu

Tyburski

Gage

. A gait analysis data collection and reduction technique. Human Movement Science. 1991;10(5):575-587.

16.

Duerr

Ormseth

Adelstein

, et al. Elevated posterior tibial slope is associated with anterior cruciate ligament reconstruction failures: a systematic review and meta-analysis. Arthroscopy. 2023;39(5):1299-1309.e1296.

17.

Eng

Winter

DA.

Kinetic analysis of the lower limbs during walking: what information can be gained from a three-dimensional model?

J Biomech. 1995;28(6):753-758.

18.

Guimarães

Giglio

Sobrado

, et al. Knee hyperextension greater than 5° is a risk factor for failure in ACL reconstruction using hamstring graft. Orthop J Sports Med. 2021;9(11):23259671211056325.

19.

Helito

da Silva

AGM

Sobrado

, et al. Patients with more than 6.5 degrees of knee hyperextension are 14.6 times more likely to have anterior cruciate ligament hamstring graft rupture and worse knee stability and functional outcomes. Arthroscopy. 2024;40(3):898-907.

20.

Hulet

Menetrey

Beaufils

, et al. Clinical and radiographic results of arthroscopic partial lateral meniscectomies in stable knees with a minimum follow up of 20 years. Knee Surg Sports Traumatol Arthrosc. 2015;23(1):225-231.

21.

Irrgang

Harner

FH.

Use of the International Knee Documentation Committee guidelines to assess outcome following anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 1998;6(2):107-114.

22.

Jauhiainen

Kauppi

Krosshaug

, et al. Predicting ACL injury using machine learning on data from an extensive screening test battery of 880 female elite athletes. Am J Sports Med. 2022;50(11):2917-2924.

23.

Juul-Kristensen

Schmedling

Rombaut

Lund

Engelbert

. Measurement properties of clinical assessment methods for classifying generalized joint hypermobility: a systematic review. Am J Med Genet C Semin Med Genet. 2017;175(1):116-147.

24.

Kamatsuki

Furumatsu

Fujii

, et al. Complete tear of the lateral meniscus posterior root is associated with meniscal extrusion in anterior cruciate ligament deficient knees. J Orthop Res. 2018;36(7):1894-1900.

25.

Keyhani

Ahn

Verdonk

Soleymanha

Abbasian

Arthroscopic all-inside ramp lesion repair using the posterolateral transseptal portal view. Knee Surg Sports Traumatol Arthrosc. 2017;25(2):454-458.

26.

Kim

Choi

Lee

, et al. Minimum two-year follow-up of anterior cruciate ligament reconstruction in patients with generalized joint laxity. J Bone Joint Surg Am. 2018;100(4):278-287.

27.

Koga

Nakamae

Shima

, et al. Mechanisms for noncontact anterior cruciate ligament injuries: knee joint kinematics in 10 injury situations from female team handball and basketball. Am J Sports Med. 2010;38(11):2218-2225.

28.

Kramer

Denegar

Buckley

Hertel

Factors associated with anterior cruciate ligament injury: history in female athletes. J Sports Med Phys Fitness. 2007;47(4):446-454.

29.

Kristianslund

Krosshaug

Comparison of drop jumps and sport-specific sidestep cutting: implications for anterior cruciate ligament injury risk screening. Am J Sports Med. 2013;41(3):684-688.

30.

Krosshaug

Nakamae

Boden

, et al. Mechanisms of anterior cruciate ligament injury in basketball: video analysis of 39 cases. Am J Sports Med. 2007;35(3):359-367.

31.

Krosshaug

Steffen

Kristianslund

, et al. The vertical drop jump is a poor screening test for ACL injuries in female elite soccer and handball players: a prospective cohort study of 710 athletes. Am J Sports Med. 2016;44(4):874-883.

32.

Larson

Bedi

Dietrich

, et al. Generalized hypermobility, knee hyperextension, and outcomes after anterior cruciate ligament reconstruction: prospective, case-control study with mean 6 years follow-up. Arthroscopy. 2017;33(10):1852-1858.

33.

Leroux

Ogilvie-Harris

Dwyer

, et al. The risk of knee arthroplasty following cruciate ligament reconstruction: a population-based matched cohort study. J Bone Joint Surg Am. 2014;96(1):2-10.

34.

Levine

Kiapour

Quatman

, et al. Clinically relevant injury patterns after an anterior cruciate ligament injury provide insight into injury mechanisms. Am J Sports Med. 2013;41(2):385-395.

35.

Mehl

Otto

Kia

, et al. Osseous valgus alignment and posteromedial ligament complex deficiency lead to increased ACL graft forces. Knee Surg Sports Traumatol Arthrosc. 2020;28(4):1119-1129.

36.

Mouton

Magosch

Pape

, et al. Ramp lesions of the medial meniscus are associated with a higher grade of dynamic rotatory laxity in ACL-injured patients in comparison to patients with an isolated injury. Knee Surg Sports Traumatol Arthrosc. 2020;28(4):1023-1028.

37.

Muller

Breederveld

Tuinebreijer

WE.

Results of osteochondral autologous transplantation in the knee. Open Orthop J. 2010;4:111-114.

38.

Myer

Ford

Paterno

Nick

Hewett

TE.

The effects of generalized joint laxity on risk of anterior cruciate ligament injury in young female athletes. Am J Sports Med. 2008;36(6):1073-1080.

39.

Nakase

Kitaoka

Shima

, et al. Risk factors for noncontact anterior cruciate ligament injury in female high school basketball and handball players: a prospective 3-year cohort study. Asia Pac J Sports Med Arthrosc Rehabil Technol. 2020;22:34-38.

40.

Nilstad

Krosshaug

Mok

Bahr

Andersen

TE.

Association between anatomical characteristics, knee laxity, muscle strength, and peak knee valgus during vertical drop-jump landings. J Orthop Sports Phys Ther. 2015;45(12):998-1005.

41.

Olsen

Myklebust

Engebretsen

Bahr

Injury mechanisms for anterior cruciate ligament injuries in team handball: a systematic video analysis. Am J Sports Med. 2004;32(4):1002-1012.

42.

Onate

Everhart

Clifton

, et al. Physical exam risk factors for lower extremity injury in high school athletes: a systematic review. Clin J Sport Med. 2016;26(6):435-444.

43.

Pasanen

Rossi

Parkkari

, et al. Predictors of lower extremity injuries in team sports (PROFITS-study): a study protocol. BMJ Open Sport Exerc Med. 2015;1(1):e000076.

44.

Perry

Knapik

Maheshwer

, et al. Lateral meniscus posterior root repair in the setting of anterior cruciate ligament reconstruction restores joint mechanics to the intact state and improves clinical function: a systematic review of biomechanical and clinical outcomes. Knee Surg Sports Traumatol Arthrosc. 2023;31(10):4474-4484.

45.

Pinczewski

Lyman

Salmon

, et al. A 10-year comparison of anterior cruciate ligament reconstructions with hamstring tendon and patellar tendon autograft: a controlled, prospective trial. Am J Sports Med. 2007;35(4):564-574.

46.

Ramesh

Von Arx

Azzopardi

Schranz

PJ.

The risk of anterior cruciate ligament rupture with generalised joint laxity. J Bone Joint Surg Br. 2005;87(6):800-803.

47.

Russek

Errico

DM.

Prevalence, injury rate and, symptom frequency in generalized joint laxity and joint hypermobility syndrome in a “healthy” college population. Clin Rheumatol. 2016;35(4):1029-1039.

48.

Ruwe

Gage

Ozonoff

DeLuca

PA.

Clinical determination of femoral anteversion: a comparison with established techniques. J Bone Joint Surg Am. 1992;74(6):820-830.

49.

Saremi

Ebrahimzadeh

Shiruei

, et al. Epidemiology of generalized ligamentous laxity in Iran: a national study including different Iranian ethnic groups and its relationship with musculoskeletal disorders. Arch Bone Jt Surg. 2022;10(3):286-292.

50.

Shimozaki

Nakase

Oshima

, et al. Partial lateral meniscus anterior root injuries during anatomical single-bundle anterior cruciate ligament reconstruction are likely to occur in women with small skeletons. Knee Surg Sports Traumatol Arthrosc. 2020;28(11):3517-3523.

51.

Shimozaki

Nakase

Takata

, et al. Greater body mass index and hip abduction muscle strength predict noncontact anterior cruciate ligament injury in female Japanese high school basketball players. Knee Surg Sports Traumatol Arthrosc. 2018;26(10):3004-3011.

52.

Sobrado

Giglio

Bonadio

, et al. Outcomes after isolated acute anterior cruciate ligament reconstruction are inferior in patients with an associated anterolateral ligament injury. Am J Sports Med. 2020;48(13):3177-3182.

53.

Sonnery-Cottet

Praz

Rosenstiel

, et al. Epidemiological evaluation of meniscal ramp lesions in 3214 anterior cruciate ligament–injured knees from the SANTI Study Group Database: a risk factor analysis and study of secondary meniscectomy rates following 769 ramp repairs. Am J Sports Med. 2018;46(13):3189-3197.

54.

Stijak

Kadija

Djulejić

, et al. The influence of sex hormones on anterior cruciate ligament ruptures in males. Knee Surg Sports Traumatol Arthrosc. 2015;23(12):3578-3584.

55.

Sundemo

Hamrin Senorski

Karlsson

, et al. Generalised joint hypermobility increases ACL injury risk and is associated with inferior outcome after ACL reconstruction: a systematic review. BMJ Open Sport Exerc Med. 2019;5(1):e000620.

56.

Svantesson

Hamrin Senorski

Alentorn-Geli

, et al. Increased risk of ACL revision with non-surgical treatment of a concomitant medial collateral ligament injury: a study on 19,457 patients from the Swedish National Knee Ligament Registry. Knee Surg Sports Traumatol Arthrosc. 2019;27(8):2450-2459.

57.

Szymski

Achenbach

Weber

, et al. Reduced performance after return to competition in ACL injuries: an analysis on return to competition in the “ACL Registry in German Football.” Knee Surg Sports Traumatol Arthrosc. 2023;31(1):133-141.

58.

Ueki

Katagiri

Otabe

, et al. Contribution of additional anterolateral structure augmentation to controlling pivot shift in anterior cruciate ligament reconstruction. Am J Sports Med. 2019;47(9):2093-2101.

59.

Uhorchak

Scoville

Williams

, et al. Risk factors associated with noncontact injury of the anterior cruciate ligament: a prospective four-year evaluation of 859 West Point cadets. Am J Sports Med. 2003;31(6):831-842.

60.

Vacek

Slauterbeck

Tourville

, et al. Multivariate analysis of the risk factors for first-time noncontact ACL injury in high school and college athletes: a prospective cohort study with a nested, matched case-control analysis. Am J Sports Med. 2016;44(6):1492-1501.

61.

Vaishya

Hasija

Joint hypermobility and anterior cruciate ligament injury. J Orthop Surg (Hong Kong). 2013;21(2):182-184.

62.

Vaudreuil

van Eck

Lombardo

Kharrazi

FD.

Economic and performance impact of anterior cruciate ligament injury in National Basketball Association players. Orthop J Sports Med. 2021;9(9): 23259671211026617.

63.

Vauhnik

Morrissey

Rutherford

, et al. Knee anterior laxity: a risk factor for traumatic knee injury among sportswomen? Knee Surg Sports Traumatol Arthrosc. 2008;16(9):823-833.

64.

Visnes

Gifstad

Persson

, et al. ACL reconstruction patients have increased risk of knee arthroplasty at 15 years of follow-up: data from the Norwegian Knee Ligament Register and the Norwegian Arthroplasty Register from 2004 to 2020. JBJS Open Access. 2022;7(2):e22.00023.

65.

Webster

Feller

JA.

Expectations for return to preinjury sport before and after anterior cruciate ligament reconstruction. Am J Sports Med. 2019;47(3):578-583.

66.

Whitney

Sturnick

Vacek

, et al. Relationship between the risk of suffering a first-time noncontact ACL injury and geometry of the femoral notch and ACL: a prospective cohort study with a nested case-control analysis. Am J Sports Med. 2014;42(8):1796-1805.

67.

Wiggins

Grandhi

Schneider

, et al. Risk of secondary injury in younger athletes after anterior cruciate ligament reconstruction: a systematic review and meta-analysis. Am J Sports Med. 2016;44(7):1861-1876.

68.

Willinger

Balendra

Pai

, et al. High incidence of superficial and deep medial collateral ligament injuries in “isolated” anterior cruciate ligament ruptures: a long overlooked injury. Knee Surg Sports Traumatol Arthrosc. 2022;30(1):167-175.

Anatomic Risk Factors for Initial and Secondary Noncontact Anterior Cruciate Ligament Injury: A Prospective Cohort Study in 880 Female Elite Handball and Soccer Players

Abstract

Background:

Purpose:

Study Design:

Methods:

Results:

Conclusion:

Keywords

Methods

Study Design and Participants

Anthropometrics and Alignment

Skin Marker–Based Measurements: Leg Length, Pelvic Orientation, and Knee Alignment

Femoral and Tibial Condyle Width

Joint Laxity

Knee AP Laxity

Genu Recurvatum

Generalized Joint Hypermobility

Mobility

Hamstring Mobility

Hip Anteversion

Navicular Drop

Injury Registration

Statistical Analysis

Results

Discussion

Conclusion

Footnotes

Acknowledgements

References